Hill repeats or interval training mess with my BGLs big-time! Any tips?

Q. Hi Allan, I’m 38 and I’ve had type 1 diabetes for a couple of years (bit of a late starter) and up till recently I’ve mostly done a bit of jogging and working out at the gym i.e. cycle classes, pump classes etc. A couple of months ago I joined a running group and on Wednesday nights we do a really hard session where we do hill repeats or interval training on the oval.

Runners Running Uphill

Meredith thinks running up hills is fun!

I like these sessions but they mess with my BGLs big-time! My BG is mostly OK before hand, but afterwards it goes really high so I correct with insulin and then later on I have a hypo.

Any suggestions? Meredith Adelaide SA

A. It sounds like your high intensity workouts could be causing an increase in stress hormones which in turn increase liver glucose production that can cause BGLs to rise. In addition, stress hormones are insulin resistant and while present can reduce the blood glucose lowering effect of whatever insulin you have on-board. Even though your levels are elevated after exercise correcting with insulin can lead to hypo problems hours later. Lots of people with type 1 get caught out on this.

Here’s a common scenario:

Let’s say you finish a tough hill session, go home, test and find you’re high. Dinner time comes around, you bolus for the carbs in the meal and add a correction dose for the exercise related high. Not so long after dinner the insulin resistance effect of the stress hormones wears off and the situation takes a turn. You go from being insulin resistant to highly insulin sensitive (from the exercise) while having a full bolus and correction insulin dose on board. This combined with replenishment of muscle glycogen used during the exercise is a predictable cause of hypoglycaemia.

If you BGLs are high for only a couple of hours after exercise, try thinking 3 to 5 hours ahead and try to avoid over reacting with too much insulin. Of course if BGLs were to stay elevated consistently beyond a couple of hours after exercise you would need to investigate further and re-think your approach. Be sure to check out the e-coach, it will help you understand what’s going on here.